1. Field of the Invention
The present invention relates to a drying apparatus for drying substrates to be processed, such as semiconductor wafers and LCD (liquid crystal display) glass substrates etc., and a method of drying the substrates.
2. Description of the Related Art
Generally, in a manufacturing process for producing semiconductor devices, there is a widely adopted cleaning method where the substrates to be processed, such as semiconductor wafers and LCD glass substrates etc. (referred to "substrates" hereinafter), are successively immersed in a process bath filled up with the chemicals, the rinsing liquids or the like. In a cleaning apparatus realizing the above method, a drying method of dehydrating moisture sticking on the surfaces of the substrates after cleaning and sequentially drying them is widely adopted. Therefore, the cleaning apparatus is equipped with a drying apparatus for realizing the above-mentioned drying method.
In general, as one of the drying apparatuses of this sort, there has been used a so-called "spin dryer" where the moisture sticking on the substrates is eliminated by rotating the plural substrates, which are held so as to stand in a row, round a rotating center parallel with central axes of the substrates.
As the conventional drying apparatuses of this kind, there is known one apparatus employing a structure where the moisture sticking on the surfaces of the substrates is eliminated by rotating a rotor which is disposed in e.g. a drying chamber and to which the plural substrates have been delivered from a transfer arm for holding the substrate standing in a row (see Japanese Unexamined Utility Model Publication Nos. 6-9129 and 6-17230) and another apparatus employing a structure where a substrate holder is detachably installed to the rotor in the drying chamber and also constructed so as to elevate by elevating means arranged below the rotor (see Japanese Unexamined Patent Publication Nos. 5-283392, 6-112186 and 7-22378).
However, the former drying apparatus has problems of not only taking up too much space for its establishment since the apparatus requires to ensure the large volume of the drying chamber for allowing the transfer arm to be inserted into the drying chamber, but lowering the drying efficiency due to a increased clearance between the drying chamber and the rotor.
On the other hand, the latter apparatus has problems that not only the drying chamber is complicated and the apparatus is large-sized, but the opportunities of sticking particles on the substrates are increased with the increased number of times for delivering the substrates.